refurbishment by steelwork_en.pdf

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Refurbishmentby steelwork

Long Carbon EuropeSections and Merchant Bars


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Combined use of new andexisting materials encourages

architectural diversity


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Contents

1. Introduction 2

2. Steel work versus consolidation levels 10

3. Refurbishment of masonry and wooden structures 26

4. Refurbishment of reinforced concrete (R.C.) structures 38

5. Refurbishment of iron/steel structures 44

6. Seismic upgrading 54

7. Additions 68

Technical assistance & Finishing 78

Your partners 79

1


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1. INTRODUCTION1.1 General 41.2 Operational aspects 51.3 Advantages of steel in refurbishment 61.4 Restoration prerequisites 71.5 Application fields 8


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Old masonry buildings often suffer damageas a result of age and the ravages of timeand therefore require structural consolidationand functional rehabilitation. In addition,more modern buildings made of reinforcedconcrete require frequent refurbishmentdue to their poor state of preservation.

In order to preserve and protect existingconstructions, many consolidation andrestoration systems have been usedin recent decades. Steelwork plays an

important role in such activity.

The restoration and consolidation processes,particularly with regards to more delicatestructural restoration of monuments,require very careful selection of newconstruction materials. These must bechosen according to the prerequisitesof the materials to be consolidated.

1.1 GeneralThe refurbishment of existing buildings and bridges isnowadays an emerging activity. Since the 1970s, weobserve that the building industry become more andmore focused on the following activities: consolidation,rehabilitation and modernisation of old buildings.

1. Introduction


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Distinction may be made between newmaterials which represent the remedy andold materials representing the sick. As aremedy we may use traditional materials:cement, mortar, reinforced concrete or steel.We may also use innovative materials: specialmortars, fibre reinforced polymers (FRP), specialmetals (high strength steels, stainless steel,etc) or even some special devices belongingto advanced systems of seismic protectionwhich use passive control technologies.

The problem, therefore, may be analysedusing a matrix, where all remedial materials(materials for consolidation) and sick materials(belonging to damaged structures) are listed,giving rise to new composite materials.

The selection of the most appropriatecombination, over all those offered by thismatrix, represents the main goal of structuralconsolidation. It appears that steelwork alwaysrepresents a remedy for all sick materials.

From a general overview of the possibleconsolidation systems, we may recognise that:

l Consolidation systems based on cementand concrete materials are widely used,especially in seismic upgrading operations,These are in the form of injections and/or reinforced concrete (r.c.) elements,but their compatibility with the masonryof old architectonic constructions isquestionable and it is particularly worthnoting that they are not reversible;

l Consolidation systems based on polymericand composite materials are very recent and,at least for the moment there is insufficientevidence to validate their durability;their reversibility is also questionable;

l Consolidation systems based on steelworkare widely and successfully used in bothcases of monumental constructions and forstandard buildings made of masonry and r.c.;

l The use of special devices is currently inits early stages, but promises to become amore widely used application in the future.

From a structural point of view, the analysisof several practical examples collectedfrom all over the world demonstrates that

appropriate selection of steelwork allowsto fulfil the complex requirements arisingat the various stages of the consolidationof damaged structures. In addition, inthe case of architectural constructions,steelwork satisfies the strict conditionsimposed by restoration principles.

D A M A G E D

S T R U C T U R E S

NEW COMPOSITE MATERIALS - Materials for consolidation

STEEL CONCRETE MASONRY WOOD FRP

STEEL ++ +

CONCRETE ++ + +

MASONRY ++ + + + +

WOOD ++ + +

1.2 Operational Aspects 1. Introduction


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The use of steelwork in consolidation and

structural restoration operations takesadvantage of the following peculiar features:

l Prefabrication allows the execution ofthe main elements by welding in theworkshop. They are tailor-made accordingto the transportation and operationalneeds in the construction yard. Theymay be easily connected by bolting;

l Reversibility is a basic property of steelwork,thanks to the use of bolted connections. Itis not applicable only for provisional but alsofor permanent constructions (Figure 1.3.1);

l Lightness of structural elements, due to thehigh strength-to-weight ratio. Transportationand erection phases are simplified andthe increase of loads is minimized;

l Reduced dimensions of the structuralelements are a natural consequenceof the high structural effectivenessof steel. The substitution and/or theintegration of the existing works with

new reinforcing elements is simplified;

l Aesthetical appearance of steel elements isfundamental when the structural synergybetween old and new materials is coupled.The architectural value takes advantage oftheir contrasting features (Figure 1.3.2);

l Speed of erection is ideal in any case,but particularly when the interventionof rehabilitation is very urgent. Itprevents further degradation andguarantee an immediate safeguard;

l The possibility of finding a variety of steelproducts on the market is important in

order to satisfy all design and erectionneeds with a large degree of flexibility. Awide range of products is available: fromhot rolled sections in the form of plates,double T, channels, angles to prefabricatedelements like cellular beams, slim floorbeams, trapezoidal sheeting and so on.

All of the abovementioned featuresconfirm steelwork as the most suitablematerial for consolidating structuralelements made of masonry, r.c., timber

and, of course, iron/steel itself.

1.3.2

1.3.1

1.3 Advantages of steelin refurbishment

1. Introduction

1.3.2


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When the building to be consolidated is ofhistoric interest, its restoration is a very delicateprocess. The restoration criteria are orientedtowards the conservation of pre-existingbuildings. The integration of new works has toensure their return to functionality. Such newworks must be clearly modern in appearance;they must be distinguishable and they mustbe reversible, through use of technologiesand materials which may be removed

without damaging the existing structure.

The various international restoration Charts,in fact, state the incongruity of reconstructionin using the methods of the past, which may nolonger be reproduced for many reasons, aboveall technological. Other reasons are related tonostalgia for traditional construction methods,tools and materials, new functional requirementsand lack of availability of old materials. At thesame time these Charts, especially in caseswhere the restoration operation involvesrestructuring with partial reconstruction, indicatethe need to use well-adapted technologiesand materials in a clearly modern way.In particular, the Chart of Venice (1964)

states that the integration works must becharacterized by the feature of our age and, when the traditional techniques areineffective, the consolidation of a monumentmust be assured by using all the most moderntools for structure and conservation, whoseeffectiveness is demonstrated by scientificdata and guaranteed by the experience .

A logical application of these principles

undoubtedly shows that steel, as a materialand its technology, has the advantage ofbeing a modern material with reversiblecharacteristics. It is particularly suited toreconcile with the materials of the past andto form integrated structural systems. Inaddition, its choice is substantially based onits high mechanical performance and on theflexibility of the constructional systems.

Construction systems based on othermaterials (cement, mortar, concrete,polymeric, composite) do not fulfil the aboveimportant prerequisite of reversibility.

In conclusion, the use of structural steel inthe rehabilitation of old monumental buildingsis perfectly in line with the recommendedcriteria of the modern theory of restoration.Steel is therefore widely used in restorationworks in all kinds of ancient monumentsand historic buildings, also under form ofspecial devices for seismic protection.

1.3.1 The use of bolted connection is an important pre-requisite for the reversibility of the solution1.3.2 The aesthetic value of a synergetic contrast between old and new materials

1.4 Restorationprerequisites

7

1. Introduction


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l Many ancient churches have been coveredby steel roofing systems, composed oftrusses and trapezoidal sheets (Figure 1.5.3).Other important buildings have beenrestructured using vertical and horizontalextensions, which are harmonised both fromstructural and aesthetic points of view.

l Entire districts of old towns in Italyhave been completely restored aftersuffering serious damage from recentearthquakes; steel components havebeen used in order to improve the seismicresistance of old masonry buildings.

l Reinforced concrete structures have beenrepaired by means of steel elementsafter being damaged or when heavierserviceability conditions are required. Theyhave also been transformed by changing thestructural scheme from the original, when a

reduction or an increase in the storey heightis carried out or when steel bracings areintroduced for seismic upgrading purposes.

1.5.1 Old industrial steel structure is transformed into apartment building (Paris, rue de lOurcq)1.5.2 A new steel skeleton inside of the existing masonry faades (Kannerland in Luxembourg)1.5.3 The new steel roof of a church (Salerno, Italy)

1.5.3

1.5.2

1. Introduction

9

+ 14.13 m

+ 11.28 m

+ 7.75 m

+ 3.97 m

+ 0.00 m


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2. STEEL WORK VERSUS CONSOLIDATION LEVELS2.1 General 122.2 Safeguard 122.3 Repairing 162.4 Reinforcement 182.5 Restructuring 20


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Chamber of Commerce, Luxembourg

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2. Steel work versus consolidation levels

2.2.3 Provisional intervention to the tympanum of the San Francisco church in Assisi (Italy)2.2.4 Temporary steelwork to sustain the faade of a building after a fire (Lisbon, Portugal)

During the application of safeguardingoperations, steelwork is mainlyused in the following ways:

l structural steel elements, in the formof scaffolding systems, offerad hoc solutions designed to achieveoptimum results and tailored to specificrequirements (Figure 2.2.3)

l

heavy steel structures (welded or boltedprofiles) and light ones (hollow sectionswith bolted joints) are effectively adoptedin safeguarding active and passiveoperations (Figures 2.2.4 and 2.2.5).

2.2.4

2.2.3The above structural steel systemsprovide the following advantages:

l light-weight

l high prefabrication

l ease of transport and erection

l economic convenience, due to

their possibility of re-use.


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2.2.5 Temporary support for the columns of the entrance of Carigliano Palace in Turin (Italy)

2.2.5



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l Speed of erection, useful when emergencyrepairs must be made as there is a risk of thedamage quickly progressing (Figure 2.3.2)

l economic convenience, thanks to thepotential of re-use (Figure 2.3.3).

2.3.1 Steel angles and ties for repairing a r.c. column2.3.2 Steel portal frames for repairing stone architraves (Berlin, Germany)2.3.3 Expo church in Hanover: modular steel structure in view of a future dismantling and reconstruction in another location

Steel structural elements offer, by meansof prefabricated types of technology,ad hoc solutions designed to achieve optimumresults and tailored to specific requirements.

Prerequisites of the steelwork components are:

l light-weight composition, allowing easeof transport and erection. They areimportant factors when it is necessary to

work in areas where space is restrictedsuch as historic centres of old towns

l reversibility, thanks to the use of bolted joints,which allows the re-use of the structurein case of dismantling (Figure 2.3.1)

Repair is the second level of consolidationof existing buildings. It involves a series ofoperations carried out on the building torestore its former structural efficiency beforeits damage. Repair, different to safeguarding,represents a definitive operation used wherewell identified damage was caused over a longperiod of time and therefore, do not requireurgent intervention. It provides straightforwardrestoration of the structural performance,

which meet minimum safety requirements.It is done without introducing any additionalstrengthening in building structures damagedby the weather and ravages of time.

As part of the repair stage, there are numeroustechnological consolidation systems based onthe use of steelwork. They can improve thestructural behaviour of masonry, reinforcedconcrete as well as timber building structures.

2.3 Repair

2.3.1 2.3.2 2.3.3



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Dames de France, Perpignan, France


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Reinforcement involves improving the structuralperformance in order to enable the buildingto meet new functional or environmentalrequirements. This consolidation level doesnot significantly affect the structural scheme.New elements are integrating the existing oneswithout substantially altering either the massor the stiffness distribution of the building.

Contrary to simple reparation, reinforcement

may be carried out at various levelsaccording to the different increases ofstrength required. Previous level of damagehas to be considered when it exists.

From a seismic point of view, the strengtheningoperation may be distinguished on twolevels: simple improvement and upgrading.

2.4 Reinforcement

2.4.1

Upgrading is carried out in order to ensurea higher degree of safety. In this casethe reinforcement work acts either on asingle part or the overall structure withoutexcessively modifying its static scheme and,therefore, the global behaviour. Improvementwork may also be carried out on singlestructural elements when they are affectedby design errors or bad execution.

Seismic upgrading work is characterised bya set of necessary steps required to ensurethat the structure is able to withstand newearthquake design loads. It may also requireextensive revision of the structural system, withcomplete modification of the global seismicperformance. In this case, this interventionhas to be classified from the structural pointof view within the restructuring operations.


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The different levels of reinforcement, fromsimple improvement to upgrading, maybe carried out through use of the sametechnological consolidation systems as thoseused for repairing. Steelwork is commonlyused to improve the static behaviour of bothmasonry and reinforced concrete buildings.Bracing systems are often used for seismicupgrading of both masonry and reinforced

concrete structures. Innovative bracing systemsare based on the use of steel eccentric bracing(EB) (Figure 2.4.1), steel buckling restrainedbracing (BRB) (Figure 2.4.2), and low-yieldsteel stiffened panels (Figure 2.4.3).

Reinforcing work is required when:

l buildings are subjected to heavier loadingconditions, due to a change of use thatrequires an increase of service loads

l existing constructions are located in anarea recently included in a new seismiczone, and are therefore subjectedto more severe loading conditions

due to the risk of earthquakes.

National regulations usually make a cleardistinction between simple improvement andseismic upgrading works. The improvementwork may be adapted in the following cases:

l when variation of the intended use occurs

l when design and/or executiondefects must be eliminated

l when the consolidation operations areapplied to monumental buildings, thatare unsuitable for extensive work.

Seismic upgrading is compulsoryin the following cases:

l super elevation or extensionof the construction, with anincrease in volume and areas

l increase of loads due to a changein the intended use

l substantial modification of the structuralsystem following renovation in comparisonwith the original or, in general, when the globalbehaviour is affected during restructuring .

2.4.3

2.4.2

2.4.1 R.C. structure upgraded by eccentric steel braces2.4.2 R.C. structure upgraded by steel BRB (buckling restrained brace)2.4.3 R.C. structure upgraded by steel panels



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Restructuring represents, in hierarchical order,the more general consolidation level of existingbuildings. It consists of the partial or totalmodification of the functional distribution,layout and volumetric dimensions. It isaccompagnied with a change of the originalfeatures of the building, including thestructural system. There are four differentkinds of restructuring work: gutting,insertion, addition and lightening.

l Gutting is the total or partial replacementof the internal part of a building with anew and different type of structure. Thisis carried out when architectural and/ortown-planning reasons require the completeconservation of the building faades,whilst the interior layout is changed forfunctional reasons (Figures 2.5.1 a,b).

2.5 Restructuring

2.5.1a

2.5.1 The old Rmerhof in Zurich is now a modern bank: a) the faade;b) the new offices of the Rmerhof are located in a steel structure inside the existing faade

2.5.2 Examples of insertion in a masonry building: a) a new steel mezzanine; b) a new steel staircase2.5.3 Steel floor in an office building in Luxembourg

2.5.1b


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l Insertion represents the introduction of newstructures or structural elements into theexisting volumetric dimension. Additionalintermediate floors or mezzanines arecreated in order to increase the usable areawithin the limits of a given volume (Figures2.5.2 a, b). An example of insertion workis the addition of large amount of self-supporting frames to house special exhibitionshowcases visible from several floors,

staircases and lift cages (Figure 2.5.3). 2.5.2b

2.5.2a

2.5.3



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l Addition is carried out for new functionalrequirements, involving the increase of theoriginal volume of the building, which maybe extended horizontally or vertically.

- Horizontal addition consists of the

introduction of new lateral volumesalongside the original structure.In these cases, aesthetic, morethan structural aspects, play agreater role due to the necessity ofharmonize different architecturalstyles (Figures 2.5.4 and 2.5.5).

2.5.4a

2.5.5

2.5.4 A new steel building in the industrial archaeology area of Catania (Italy),called Le Ciminiere, where the old masonry buildings have been restored with a steelwork

2.5.5 A new steel building inside historical buildings in the city centre of Udine (Italy)

2.5.4b


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Abbey of Neumnster, Luxembourg


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Exhibition hall in Cologne, Germany


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- Vertical addition requires the extensionof the height of the building by one ormore storeys above the existing structure.Depending on the amount of additionalweight, it may be necessary to re-checkthe load-bearing capacity of the originalstructure. Some consolidation work mayhave to be done prior to this addition.This problem is particularly significantin areas of seismic activity, where theoverall behaviour of the building is stronglyinfluenced by the addition of new massesparticularly on the upper levels. The needto minimize the additional structuralweight makes steel the most suitablematerial, thanks to its high strength/low weight ratio (Figures 2.5.6 a, b).

l Lightening , as opposed to vertical addition,may include the removal of one or more ofthe upper floors due to the need to reduce thelevel of stresses in the structure. This scopemay be achieved by means of steps involvingthe replacement of the original floors, roofsor other structural elements with new lightermaterials. The replacement of heavy woodenfloors with light steel I-section and corrugatedsteel sheets as well as the consolidation ofold roofs with steel trusses is very common.

Restructuring is appropriate when themodification of the functional layout of abuilding requires the introduction of newvolumes and areas or when new regulationsrequires the modification of the resistantstructural system. This is also necessary

2.5.6a 2.5.6b

for extensively damaged buildings whichrequire the complete modification and theupgrading of the structural system.

Conservation of existing buildings and theirintegration with new clearly distinguishableand reversible work represents a classicalrestructuring operation, which must be basedon the modern theory of restoration.

A logical application of the restorationprinciples undoubtedly shows that steel and itstechnology have the necessary prerequisitesof a modern material with reversiblecharacteristics. It is particularly suited to beused alongside traditional materials, thusforming an integrated structural system.

2.5.6 a) A steel super elevation of an old masonry mill in Briatico (Calabria, Italy), now a sporting club;b) details of the new steel structure at the second floor



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3. REFURBISHMENT OF MASONRY AND WOODEN STRUCTURES3.1 Consolidation of masonry structures 283.2 Masonry building consolidation 303.3 Masonry building degutting in Paris (France) 313.4 Consolidation of wooden structures with steel elements 323.5 Replacement of wooden trusses by steel trusses 343.6 Roofs made of steel and glass 37


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3. Refurbishment of masonry and wooden structures

The load-bearing capacity of masonry elements must be

improved when damages caused by external unexpectedloads occured (i.e. earthquake) or when the wholestructure must be upgraded to resist to higher loadingconditions imposed by a new use of the building.

3.1 Consolidationof masonry structures

A classic system for improving theload-carrying capacity of masonry elementsconsists of injections of pressurised mortar orcement, combined or not with anchor steelbars. If it is the case the use of stainless steelis advisable in order to avoid future damagecaused by corrosion. However this systemis not reversible and is therefore contraryto the basic principle of restoration.

By observing some old masonry buildingsduring demolition, it is evident that steel

frames were originally used for reinforcingthe masonry itself (Figure 3.1.1). Thismeans that steelwork represents themost suitable system of consolidation.

Damaged masonry columns, are usually repairedby means of steel hoops. The lateral restrainingof the material produces a significant increase ofthe vertical load-bearing capacity (Figure 3.1.2).

In the case of circular columns, the hoopsmay be made of vertical plates withrectangular cross-sections, which arereinforced by horizontal steel rings. In thepast, the prestressing operation was madeby heating and the subsequent contractionof the rings. Nowadays, two half rings maybe prestressed with bolts (Figure 3.1.2).

In the case of square or rectangular cross-

sections, angle shapes may be used as verticalelements in the corners. They may be connected

in different ways: by means of internal tiesintegrated by batten plates, by means ofchannels connected by external ties or bymeans of horizontal rings (Figure 3.1.2).

When it is necessary to transfer a significantproportion of the total vertical load fromthe masonry panel to a new steel structure,the new steel columns may be insertedinto proper grooves or simply connectedto the masonry (Figure 3.1.3).

In case of openings, the strength of themissing part of masonry may be recoveredwith steel beams on the upper part or steelframes around the opening (Figure 3.1.4).Also masonry arches may be reinforcedby means of steelworks (Figure 3.1.5).

3.1.1


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3.1.1 Steel frame inside the masonry walls during ademolition operation in Manchester (United Kingdom)

3.1.2 Consolidation of masonry columns by means of steelwork3.1.3 Consolidation of masonry walls by means of steelwork3.1.4 Details of the steelwork around a new window3.1.5 Consolidation of masonry arches by steelwork

3.1.5

BATTEN PLATE

BOLT

ANGLE

THREADEDTIE BAR

ANGLE

THREADEDTIE BAR

ANGLE

HOOPS

3.1.2

3.1.33.1.4


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3. Refurbishment of masonry and wooden structures3.2 Masonrybuilding consolidation:the re-use of a building

complex in Bologna (Italy)

A large building complex in Bologna hasbeen completely transformed and is nowmultipurpose, containing a hotel, apartmentsand shops. Steelwork has been selected bothfor structural and architectural reasons.

The 5- to 6-storey masonry buildings aroundthe perimeter have been consolidated bykeeping their original feature. Some buildingsin the central part, seriously damaged, weredemolished and replaced by three new 2- to3-storey buildings. Moment-resisting steel

frames were inserted in both directions.

The insertion of two levels of steel frameswith independent foundations inside theexisting masonry allowed to build a series ofstairs and walkways at the two levels belowand around the internal court. These newframes are made of HE sections. The erectionprocess of the inserted steel elements and thesubsequent demolition of the masonry werecarried out without any safeguarding works.

The internal court is characterised by a numberof steel staircases (Figure 3.2.1) connecting thefirst floor.

3.2.1 Detail of staircases in the internal court of the building block in Bologna (Italy)

3.2.1


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3.3 Gutting ofmasonry building andinsertion of a new

steel structure(Paris, France)

3.3.1

Some important buildings in Paris haverecently been refurbished through gutting.Two buildings in boulevard Haussman atnumbers 6-8 and 54 have been completelyemptied and a new steel structure insertedinto the existing faades (Figure 3.3.1).

The AGF building at Ilot Lafayette has beenrenovated by extensive use of castellatedsteel beams. Another building in placedIna 7 has been gutted and a new8-storey steel structure erected inside.

A group of buildings, built between the beginningof the 20 th Century and the 1950s, has beenrenovated and converted into a unique modernoffice building - called Le Centorial with anew parking area in the basement. In much ofthe above work, both principal and secondarybeams of the floor structures are castellated, inorder to allow straightforward installation oftechnological equipments.

3.3.1 Restoration of the AGF building in Paris (France)


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3. Refurbishment of masonry and wooden structures3.4 Consolidationof woodenstructures with

steel elements

3.4.3b

3.4.3aMasonry buildings are usually integrated byfloor structures made of timber. It is veryoften necessary to strengthen the timberparts (beams and deck) as they are usuallyin a poor state of conservation due towood fungus, parasites and maceration.

Many systems have been proposed toimprove the load-carrying capacity ofbeams. There are two main ways of doingthis depending on whether it is convenientto work from underneath or from above

the beams in order to insert additionalsteel elements (Figures 3.4.1 a, b).

In the first case, steel reinforcements may beadded in different forms underneath, from simpleplates to hot-rolled H or U sections, which maybe adapted to individual cases according to thefeature of the structure to be consolidated.

When the original shape of the beam mustbe preserved because it is of particularhistorical interest, it is necessary to

implement the second method, namelyby working from above the beam.

The final result is a composite wood/steelsystem, which considerably increases thestrength and rigidity of the original structure. Inall cases, such interaction between the new andthe old material must be guaranteed by usingappropriate connecting systems from simpleties to different types of studs (Figure 3.4.2).

Many old wooden bridges are examples ofhistorical constructions which have beenpreserved through use of steelwork. Twosignificant examples are: the Academiapedestrian bridge in Venice and the Buchfahrtbridge near Weimar in Germany, whoserestoration protects the structure in its daily useunder heavy traffic loads (Figures 3.4.3 a, b).


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3.4.1 Consolidation systems for wooden beam by means of steel elements:a) operating from the bottom to the top;b) operating from the top to the bottom, giving rise to a steel/wood composite structure

3.4.2 Multi-composite solution for consolidating an old wooden floor3.4.3 Buchfahrt Bridge near Weimar (Germany)

3.4.1b

3.4.2

ooring

secondarybeam

r.c. slab platform

tie rod

main beam

tie rod

main beam

tie rod

cold formed C proles

cold formed prolescold formed proles

3.4.1a


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3.5 Replacementof wooden trusseswith steel trusses


3.5.2a 3.5.2b

3.5.1 Steel elements for the consolidation of a wooden truss3.5.2 a) A new roof made of steel trusses integrated by an inferior steel grid for creating a diaphragm effect;

b) steelwork for covering the abside of an old masonry church

strenghtening gusset s=8mm

M12 tie rods

cold-formed C prole

welded gusset

M12 tie rods

M12 tie rods

3.5.1


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Wooden trusses are very often damaged bythe ravages of time. In some cases they maybe repaired by the addition of steel platesto the connections or along the elements(Figure 3.5.1). Often this type of repair isnot carried out, the best solution being thereplacement of the whole timber truss systemwith a new roof made of steel profiles.

Examples of this type of work on historicalbuildings, like palaces and churches, arepresent in many European countries. In

particular, many churches and historicalbuildings have been retrofitted by replacingthe old timber roof with steel trussesand finished with trapezoidal sheets.

Where the church is located in an areaprone to earthquakes, the new steel trusses

may be integrated with a horizontal grid,in order to rigidly connect the top of themasonry walls and, therefore, create adiaphragm effect (Figures 3.5.2 a, b).

A significant example of a new steel roofis Naples Cathedral (Figure 3.5.3). Thenew whole roof of the Ducal Palace inGenoa is made of steel profiles (Figure3.5.4). Many old buildings of the RoyalIron Mill of Mongiana in Calabria have beenrenovated by means of new steel roofs.

A roof-reversal operation has been carried outin Gevelsberg (Germany) in a building whichwas formerly used as a workshop and is nowa garage and warehouse (Figure 3.5.5).

3.5.3 The main faade of the Naples Cathedral (Italy)3.5.4 The new steel roof of the

Ducal Palace of Genoa (Italy)3.5.5 Roof renewal in Gevelsberg by means

of steel beams and trapezoidal sheets

3.5.3

3.5.4

3.5.5

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Reichstag in Berlin, Germany


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3.6 Roofsmade of steeland glass

3.6.1 The Inner Court of the Museum of Hamburg (Germany), covered by steel and glass3.6.2 The former regional parliament in Dsseldorf (Germany)

Covering the internal courtyards of historicalbuildings is a relatively new activity, which isvery often used to extend the functional layoutof the inside of the building. Two significantexamples of glazing roofs are: the innercourtyard of the Museum of Hamburg (Figure3.6.1) and the extension of the Art Gallery K21of Dsseldorf, opened in 2002(Figure 3.6.2).

3.6.1

3.6.2


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4. REFURBISHMENT OF REINFORCED CONCRETE(R.C.) STRUCTURES

4.1 Consolidation cases 404.2 Change of structural scheme: gymnasium in Cant (Italy) 43


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The increase of the loadbearing capacity in r.c. columnsmay be obtained by adding, in one or two directions, acouple of hot-rolled steel sections, which are connectedtogether by means of appropriate ties. The use ofchannels, angles and plates makes it possible to obtaina continuous resisting perimeter, where the prestressingeffect is realized by means of bolts (Figures 4.1.1 a, b).

4.1 Consolidation cases

The strengthening as well as the repair of r.c.beam-to-column joints is usually achievedthrough the use of angles and batten plates,which are located around the r.c. members(Figure 4.1.2).

The steelwork is welded and sometimes glued tothe concrete surface. The size of the additionalelements depends on the requested amount ofincrease in shear and bending capacity.

4.1.1b

4.1.1a

distribution plate

C prole

Non shrinkage mortar


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4. Refurbishment of Reinforced Concrete (R.C.) Structures

41

The increase of the inertia of r.c. beams may beobtained by connecting the r.c. section to steelplates or proles, by means of bolts or ties andglue (Figure 4.1.3). The same system may beused to strengthen oor structures made ofr.c. and clay blocks. Mixed concrete and brickoors may be strengthened using the followingmethods (Figure 4.1.4):

l plating the bottom of the individualconcrete beams by means of steelplates, without breaking the tiles;

l reinforcing the individual concretebeams by means of steel sections;

l inserting H profiles between concretebeams in suitable openings;

l strengthening with U channels connectedbelow each concrete beam.

4.1.1 a) Consolidation of r.c. columns by means of steel elements;b) details of batten plates and angles system

4.1.2 Consolidation of an r.c. beam-to-column joint by means of batten plates and angles4.1.3 Consolidation of r.c. beams by means of steel elements4.1.4 Consolidation of r.c. floor structure by means of steel elements

Block Floor

Steel channel

SlabJoist

Angle

Batten

Angle

Angle

Batten

Plate

Angle

4.1.2

4.1.3

4.1.4


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4.2.2

4343

4. Refurbishment of Reinforced Concrete (R.C.) Structures

43

An old industrial building in Cant in the provinceof Como (Italy) has been converted into agymnasium using structural steelwork to achievea change of layout in the original reinforcedconcrete structure (Figure 4.2.1).

The original layout consisted of a two-storeyreinforced concrete frame with intermediatecolumns (Figure 4.2.1 a). The conversion to a

gymnasium required completely stripping theinterior of the building and eliminating thecentral columns and intermediate oor.The existing roof structure is now supportedby new steel portals arranged in pairs on eitherside of the existing columns and inserted intothe external walls (Figure 4.2.1 b).

4.1.5 Steel bracings for seismic upgrading of r.c. frames4.2.1 An existing industrial r.c. building in Cant (Italy) has been converted into a gymnasium, by drastically modifying the structural scheme4.2.2 The coupled steel portals are visible on the faade

r.c. column

r.c. beam

On the front faade, the portals pierce theperimeter walls in such a way as to create aninteresting architectural motif relieving themonotony of the faade (Figure 4.2.2).

Inside, the rafters of the new frame support theexisting reinforced concrete roof truss directly.

4.2.1a 4.2.1b

4.2 Change of structural scheme:gymnasium in

Cant (Italy)


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5. REFURBISHMENT OF IRON/STEEL STRUCTURES

5.1 Consolidation of iron and steel structures 465.2 Change of use: rue de lOurcq Building, Paris (France) 51


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5. Refurbishment of iron/steel structures

Resistance of iron and steel in construction has graduallyincreased as improvements in manufacturing and productionhave taken place. In the 19 th century, allowable stresses forcast iron were around 20 MPa and for wrought iron around100 MPa. Current acceptable stresses for steel, which areprovided in the latest standards for design of steelwork, arevery much higher. The strength of existing iron and steel

structures obviously needs to be considered in relation to thestandards in force at the time of original construction, althoughwith extensive testing it may be possible to justify a slightincrease in the allowable stresses specified at that time.

Various techniques may be employedto strengthen existing steel beams:

l plates or profiles may be weldedto top and bottom flanges;

l channels or H-sections maybe welded onto flanges;

l plates may be welded between top andbottom flanges to form a box section;

l working from above, a reinforced concreteslab may be cast and attached to the beamsbelow using suitable connectors (angles,

T-sections, bars, studs, etc) welded to thetop flange to develop composite action.

In all cases, the combined use of new andexisting materials must be carefully considered.If bolting is to be used the initial loss of strengthof the existing member whilst the bolt holesare drilled will need consideration, as thistemporary condition may prove to be critical.

If welding is used as an alternative, thespecification of the welding technique mustbe compatible with the existing material.

Weldability or improved welding properties ofthe material plays a fundamental role in therefurbishment of existing iron/steel structures.In many cases the historical documentation

is missing or inadequate, but it is well known

existing elements

added elements

5.1 Consolidation of ironand steel structures

that the metallic materials of the nineteenthCentury were not generally suitable for welding.

The few basic rules to be considered are:

l cast iron may not be welded;

l wrought iron may be welded, provided thatappropriate recommendations are followed;

l mild steels may be welded underappropriate conditions by usingelectrodes which are compatible(generally low hydrogen electrodes).

5.1.1


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When it is not possible to work fromunderneath, the additional steel element maybe connected to the top flange (Figure 5.1.4).

Particular attention to the state of preservationis required when attaching old steel to new one.In many cases welding is not allowed due tothe impure composition of the old material,and bolting is therefore advisable.

Many steel/iron constructions (buildingsand bridges) of the 19 th century belongto the cultural heritage of historicalmonuments (Figure 5.1.5). The re-use ofold industrial buildings belonging to the so-called industrial archaeology is today anemerging activity. The Culture & ExhibitionCentre Century Hall in Bochum was aformer blast-hall of an old foundry, whichwas refurbished in 1993 (Figure 5.1.6).

The Exhibition Hall in Cologne has recentlybeen restored and located inside an old steelstructure covered by arches (Figures 5.1.7 a, b).

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5.1.4 Reinforcing of floor steel beams by adding steel section to the top flange5.1.5 The renovation of the old Gare dOrsay in Paris, now re-used as a Museum5.1.6 The new Culture & Exhibition Centre Century Hall in Bochum (Germany), obtained from the transformation of a former industrial building5.1.7 The new Exhibition Hall in Cologne (Germany) after the restoration of the existing steel structure

5.1.7a 5.1.7b

5.1.6

Double T section

Slab

Concrete

Clay blockDouble T beam

Floor

SlabConcrete

Floor

Protection

Clay block

Clay block

Double T beam

5.1.4


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An old machinery building of the coal mineZeche Zollern in Essen (1904) has beenrefurbished and transformed into a museum.

Within the industrial archaeology, thegasometers represent very symbolic structures,which are re-used for many differentpurposes. The gasometer of Oberhausen(Germany) has been extended and usedas an exhibition hall (Figure 5.1.8).Two

gasometers in Athens have been re-used asan office building and auditorium in the newMuseum of Maria Callas (Figure 5.1.9).

5.1.8

5.1.9


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This building is situated at 135 to 145, rue delOurcq and at 24 to 36, rue Labois-Rouillon inParis. It was an industrial building originally usedas a depot and baling plant for old paper andfabric, and later as a furniture warehouse. Theproperty had to be adapted for its new role asan apartment block, whilst keeping the featuresof its late 19 th century industrial architecture(Figure 5.2.1).

The depth of the building did not allow to usethe whole of the floor area for apartments. Ittherefore proved necessary to form a void in thecentral part.

The architects made use of this constraintto create a unique interior space, stronglydefined yet highly differentiated. It formeda kind of backbone which services all of theapartments, allowing them to open onto aquiet garden area away from the noise of thestreet and providing them with natural daylight.This layout gives the apartments individualcharacter and a private interior street.

5.1.8 The Gasometer in Oberhausen (Germany) has been extended and re-used as an exhibition hall5.1.9 The Maria Callas Museum in Athens (Greece)5.2.1 The existing faade of an old industrial building in rue de lOurcq in Paris (France)

Small business premises have been built on theground floor, along rue de lOurcq and on thelittle square. This location was chosen becauseof the easy access and the liveliness that itbrings to the street. All of the floors, beams andcolumns of the steel structure inside the buildingbuilt at the beginning of the 20 th centurywere in an acceptable state with no majordamage or excessive corrosion. The structurewas very well suited to the change of buildinguse since its components had been originallydesigned to support heavy industrial loads.

5.2 Change of use:rue de lOurcq Building,Paris (France)

5.2.1


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The internal columns made of cast ironare supporting the floors on a structuralgrid measuring 4m by 4m. Where the newarrangement created small loads, the columnswere left in their original condition (Figure 5.2.2).

To carry the heavy loads the columns were

encased in a square section of reinforcedconcrete. The columns are supported horizontallyat mid-height by the beams of the mezzaninefloors or by the reinforced concrete faade.

The beams were too narrow and some ofthem were off-centre. In most cases theywere arranged in pairs, a flange width apart.Occasionally, a main girder was made up oftwo beams of different depths. Sometimesthe beams were jointed, sometimes single.The connections were as varied as the beams.All the joints have therefore been checkedand strengthened where necessary and thebeam supports at the columns reinforced.

The original floors were made of joistssupporting brick and clinker vaults that werecovered with reinforced cement mortar. Incertain areas the floor was strengthenedby concrete which covered the wholedepth of the joists. In other areas floorshad to be demolished or reinforced.

The whole building is covered by a saw-tooth roof arranged parallel to the street.

The north-facing slopes were glazedand the southern-facing slopes weretiled. The span of the saw-tooth trussesis twice that of the floor beams at the

lower level. The columns supporting theroof are generally IPN 260 sections.

The conversion to provide the inner courtyardrequired the removal of several north lights.The orientation of the building and itssaw-tooth roof form made it ideal for theinstallation of solar panels for heating water.

It was necessary to provide fire resistance ofhalf an hour for the floors and the supportingstructure. The fire resistance was achieved in theapartments either by encasing in approximately70mm thick reinforced concrete where thecolumns fell within the partition walls betweenapartments or by intumescent paint. In thebusiness premises, rock wool casing (mouldedor padded) was used with a protective plastercovering. The steel structures were keptvisible in the apartments (Figure 5.2.3).

5.2.2 The original columns in the internal court5.2.3 Internal view of an apartment

5.2.2

5.2.3


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Central Railway Stationin Leipzig, Germany

53


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6. SEISMIC UPGRADING

6.1 Bracing Systems 566.2 Seismic upgrading of masonry buildings: the Capodimonte district in Ancona (Italy) 596.3 Passive Control Systems 616.4 Anti-Seismic Steel Roofings 626.5 Seismic upgrading by gutting: The Court of Justice in Ancona (Italy) 65


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6. Seismic upgrading

The use of steel braces is very effective in strengtheningboth masonry and reinforced concrete structures againstearthquakes. It allows for the introduction of shear walls withlattice scheme, which has the two purposes: increase theresistance of the structure to horizontal forces and balance thedistribution of internal rigidity with respect to the shear centre inorder to minimise dangerous torsional effects (Figure 6.1.1).

With regards to masonry structures, the

steel braces may be located inside or besidethe masonry wall and must be connectedto the floor structures (Figure 6.1.2).

B

A

A

A - A

B - B

6.1 Bracing Systems

6.1.1


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6.1.4


Several seismic upgrading operationshave been carried out all over the worldthrough use of steel braces in the reinforcedconcrete frame meshes (Figure 6.1.4).

In the case of steel structures requiringupgrading to resist seismic activity becauseof the recent inclusion of the building in anew seismic area, strength and ductility must

be improved, particularly in the joints.

Appropriate systems for strengthening thetwo classical types of joints (both rigid andpin-ended), by means of the introductionof stiffening elements, may be used. In thecase of rigid joints, the bending capacityis then improved. In the case of pin-ended joints, the integration of stiffeners isdesigned to introduce a given capacity toresist bending moments, which is practicallynon-existent in the original joint.

The improvement in resisting horizontal actionsmay be easily achieved by increasing the cross-section of diagonal bracings in case of bracedstructures or by introducing new bracings inthe case of movement-resistant structures.


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There is an interesting example of seismicupgrading in the renovated district ofCapodimonte in the historic centre ofAncona, the oldest part of the town,formerly inhabited by fishermen.

The masonry buildings were in an advancedstate of decay caused by the extensive damagesuffered during the earthquakes of 1972and 1936 or by the bombardments sufferedduring the second world war. This situationhad led to the precautionary evacuation of

practically all the inhabitants of the district.

In all buildings with two or three storeysabove ground level, the solid brick and dressedstone walls had widespread cracks and themortar had completely lost all consistency.The need for a reliable method of restructuringthese buildings led to rejection of the traditionalmethods of consolidation based on localstrengthening of the individual constructionalcomponents. Preference was given to asolution whereby the task of transferringthe loads to the foundations was completelyentrusted to a new structural system.

The work carried out comprised a steelstructure inserted into the perimeter andinternal walls, integrated with horizontalstructures of steel sections and corrugatedsteel sheets. The new steel skeleton, suitablyconnected to the bracing walls, forms anstructural system independant of both verticaland horizontal loads, particularly designed towithstand the effects of seismic activity.

6.2 Seismic upgrading ofmasonry buildings: theCapodimonte district in

Ancona (Italy)

6.1.4 The steel cross-bracings in an apartment building in Berkeley (California, USA)6.2.1 The Capodimonte district in Ancona: details of the new

steel structure inside of the masonry building


6.2.1

The steel skeleton is completely autonomousand independent of the existing walls, which aredowngraded to simple partition walls and do notrequire any load-bearing capacity (Figure 6.2.1).

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The refurbishing work was carriedout in the following stages:

l creation of openings in the lower part ofthe walls to contain the newly reinforcedconcrete foundations (Figure 6.2.2);

l positioning of the anchoring boltsand base plates (Figure 6.2.3);

l

after creating suitable vertical channels inthe perimeter walls, erecting steel columnsover the full height and temporary bracingof these at floor levels (Figure 6.2.4);

l constructing roof structures with trussesand purlins and finishing off with the existingcovering of roof tiles (Figure 6.2.5);

l from the top floor, demolition of internalwalls and the corresponding floor and thenreconstruction of the new floor with mainand secondary beams, corrugated steelsheets and cast concrete (Figure 6.2.6):

l building up the reinforced concretewalls of stairway cores with stepsand landings cast on site;

l final connection of the steel framework tothe existing walls and reinforced concretestaircases, then fixing with sealing concrete;

l completion with partitions, plastering,floor coverings and finishes.

The external walls, suitably restored, still retaintheir architectural and enclosing or protectivefunction, but are relieved of their role asmain load-bearing elements (Figure 6.2.7).

6.2.2

6.2.3 6.2.4


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The control of the structural responseproduced by earthquakes may be carriedout by means of various systems based ondifferent concepts, such as modifying massesor damping as well as the production of passiveor active counter forces. Following the passivesystems, which do not require an externalpower source, the properties of structure(period and/or damping capacity) do not varydepending on the seismic ground motion.

The energy-absorbing devices filter the seismicforces and thus considerably reduces the seismicimpact on the protected structure. The use ofpassive control techniques in the refurbishing ofexisting buildings is a relatively new issue. Thereplacement of an old wooden roof with a newsteel structure creates the suitable conditionto conveniently apply the passive controlconcept to the masonry building with the aim ofimproving the seismic resistance of the building.

It is widely recognised that in order to ensureadequate protection against seismic activityin a masonry building it is necessary to ensureone or more floors to be able to act as rigiddiaphragms. Only if this condition occurs, theefficient transmission of the horizontal forcesto the vertical walls could be assured. In orderto guarantee the diaphragm effect in thecase of a masonry single- storey building (forinstance the nave of a church), the rigid links,created between masonry and roof structures,may cause certain problems to masonry wallsdue to thermal variations depending on the

geometrical and mechanical features of thestructural scheme (span-to-height ratio).

In contrast, if the rigid link is not assured,the structure may breathe normallywithout transmitting stresses to themasonry. The diaphragm effect is notproduced in case of earthquake.

The oleo-dynamic dampers (also called shock-block transmitter units) are able to resolvethese contradictory issues, because theydemonstrate the two different behaviours

when required. Under thermal loads, wherespeed of application is very slow, the oleo-dynamic dampers act as sliding bearings:the structural system of the roof is staticallydetermined and no additional stresses ariseas a consequence of thermal variations.

During an earthquake, the devices act as fixedrestraints owing to the high speed of loadapplication: Under these conditions the structuralsystem becomes redundant, with significantimprovement in the overall seismic behaviour.The devices have a plastic threshold: whenthis is exceeded, significant energy dissipationoccurs, which is able to reduce the effects ofthe seismic action on the masonry structure.

6.2.2 The new foundation and the column base6.2.3 The location of the steel column in the existing masonry wall6.2.4 Growing of the steel structure inside the masonry6.2.5 The new steel roof 6.2.6 The new floor structure6.2.7 The Capodimonte district in Ancona: the old facades are kept as they were,

without showing the internal seismic resistant steel structure

6.2.5

6.2.6

6.2.7

6.3 Passive ControlSystems


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l The church of St. GiovanniBattista (Carife, Italy)

The restoration project of the St. GiovanniBattista Church in Carife near Avellino is thefirst example of application of oleo-dynamicdampers in the field of monument. In 1990. Anew steel roof structure consisting of a planegrid-work and triangular trusses was built toprovide a box-like behaviour of the masonry

structure under seismic loads (Figure 6.4.1).Besides, oleo-dynamic restraints wereplaced on one side of the grid-work, inorder to obtain a fixed or a free restraintsituation at the base of the trussesaccording to the loading condition.

The devices adapted for the church have beencalibrated in order to act as fixed bearingsunder the action of the design earthquakein line with Italian regulations, causing thedissipative behaviour to occur in case of amore severe earthquake. The test results onthe devices confirmed the design assumptions.

l The New Library of the UniversityFederico II (Naples, Italy)

The same concept used on theaforementioned Church was appliedlater on (1996) in the structuralrestoration of the Mathematics buildingin order to create a new library.

This work was carried out as part of an

extensive project to restore all monumentalbuildings which date back over a century,belonging to the original part of theold central University of Naples.

The upper floor structure (coveringan area of 16 x 32 meters) was re-built during the 1950s by means of r.c.beams (16 m clear span) with mixedclay blocks and r.c. cast elements.

This structure was in very poor conditiondue to the steel rebar corrosion and thesuperficial degradation of concrete.

6.4.1 The church of St. Giovanni Battista in Carife (Italy): the new steel roof made of trusses and horizontal grid6.4.2 The new steel roof with passive control devices: oleo-dynamic cylinder

The decision was made to demolish and tobuild a new steel structure, using castellatedbeams and metal decking. A system of 24oleo-dynamic cylinders and neoprene bearingdevices have been used for the support of thenew steel beams on the top of the perimetermasonry walls, providing an expected dualbehaviour under serviceability conditionsand in case of earthquake (Figure 6.4.2).

6.4 Anti-SeismicSteel Roofings

6.4.1 6.4.2


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Court of Justice of the EuropeanCommunities, Luxembourg


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l The industrial building of Sarno (Salerno, Italy)

The seismic upgrading work was carried outon an existing masonry single-storey industrialbuilding. Due to the large span of the buildingand to the absence of intermediate walls, theuse of a steel reticulated diaphragm appearedas the most appropriate choice because ofits lightness and in-plane stiffness (Figure6.4.3). Also, suitable energy dissipation

devices placed at supports of roof trusseshave been introduced in order to provide asignificant amount of energy dissipation.

To this purpose, both oleo-dynamic andplastic threshold devices have been used(Figure 6.4.4), in order to respond adequatelyduring daily and seasonal thermal changes tothe roof, as well as low-to-moderate intensityearthquakes and severe earthquakes.

A comprehensive study of the seismicresponse of the structure, carried outby means of a dynamic time-historyanalysis, shows the effectivenessof the adopted solution.

6.4.3 The new steel roofing structure made of trusses and horizontal grids during erection (Sarno, Italy)6.4.4 Special devices for passive control in the new steel structures of Sarno (Italy): oleo-dynamic cylinder6.5.1 The historical faade of the Court of Justice in Ancona6.5.2 The internal steel structure during erection

6.4.4

6.4.3


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The building was completely gutted andrestructured to house the new courtoffices. The arrangement of the windows,cornices and all ornaments in the masonryfaades characterising its neo-renaissancestyle were preserved (Figure 6.5.1).

The main load-bearing structure consists offour reinforced concrete towers measuring9x9m, containing stairs, lifts and floor services

and located at the corners of the innercovered courtyard. These towers provide thevertical support to the roof and the five floorssuspended from it, as well as horizontal stabilityto resist the effects of seismic activity.

The system of suspension in the roofconsists of four pairs of truss girderssupported on the inside edge of the fourreinforced concrete towers, thus markingthe perimeter of the covered courtyard.

Each pair of trusses forms a box girdermeasuring 1.80m wide, 4m high with cross-shaped wall diagonals (Figure 6.5.2).

6.5 Seismic upgrading bygutting: The Court of Justicein Ancona (Italy)

6.5.1

6.5.2


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All the truss members (chords, vertical anddiagonal bars) are made of steel I-sections,connected by means of bolted gusset plates.The inner ring made up of four pairs of girderswith a span of 21,40m represents the keycomponent of the steel skeleton which the othermembers of the structure are connected to:

l inside the core the beams supporting thedome skylights, which illuminate the innercourtyard rest on the upper truss nodes;

l outside the core the cantilever beamswhich cover the zone outside theperimeter defined by the four towers areconnected to the lower truss nodes;

l the tension rods for the five suspendedfloors below start off in groups offour from the truss nodes of the innerbottom chords (Figure 6.5.3).

The five floors suspended from the roof girdersare attached to the four zones measuring9x20m between the four towers (Figure6.5.4). They consist of structural steel beamsand joists supporting composite slabs.

The main interior beams are suspendedby tie rods from the box girder ring, whilston the outside they rest on the perimeterarea in RC between the four towers andthe exterior faades of the building.

They were connected by welding to suitableplates previously sealed in the concrete. All

other structural components were assembledon site using bolted connections. The individualelements were fabricated in sizes convenient fortransportation inside the historic city centre aswell as erection within a highly built-up area.

6.5.3 The vertical ties from the top reticular steel girder in the court of justice in Ancona (Italy)6.5.4 The five suspended floors facing the inner courtyard of the Court of Justice

6.5.3

6.5.4


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7. ADDITIONS7.1 Expansion of area: Van Leer Office Building in Amstelveen (The Netherlands) 707.2 Vertical extension super elevation: Building in Victoria Street, Toronto (Canada) 717.3 Addition in historical buildings: the old factory of Briatico and the Cultural Centre of Succivo (Italy) 727.4 Vertical extension by suspension: the Jolly Hotel in Caserta (Italy) 737.5 The Reichstag in Berlin (Germany) 747.6 Various horizontal and vertical extensions using steelwork in Germany 75


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7. Additions

The office building was built at theend of the fifties to accommodateabout 500 employees, but due tothe decentralisation of the Van Leerorganisation, only about 300 staffhave worked here in recent years(Figure 7.1.1)Furthermore, as with most buildingsdesigned before the oil crisis, theenergy costs were very high.

7.1 Expansion of area:Van Leer Office Buildingin Amstelveen

(The Netherlands)

c) Fitting the jacks- when the load is carried by the support

structure, cut the lower columns- fit lifting jacks on support- sawn-off columns on floor at 4.70m below

the existing floor and at +6.60m for re-use- support structure carries floors at

+6.60m, +12.20m and constructionat +8.25m for short duration

- lifting jacks in highest position

d) Lowering the floor- remove bolts from joints between

columns of the first structureand floor beams at +6.60m

- maximum disalignementbetween the jack 10 mm

- check for final disalignement and for skew

e) Floor at level +4.75m- the floor is now at level +4.75m- the lower joints are welded- the removed column section

is moved up and welded.- when the column is completely welded, the

jacks and support structure can be removed

f) 2nd floor at +8.50m- fitting the hollow prestressed slabs- pour concrete screed and joints- fitting faade walls- finishing the whole building

a) Cross section of existing building - demolish all inner walls- demolish faade walls- free columns- shut off main electricity and heating system

b) Fitting the steel construction forthe new floor and the temporarysupport structure (in yellow)

- one (light column) for the new floor to becreated at +8.50m and the other one inthe centre to support the existing floor.

- make use of the existing floor at 6.60mto build the new floor (in red)

- bolting of the joints- support structure from floor at +8.25

shored on all sides to carry load tofoundations

- propping of this first structure which issupporting the new floor (+8.25) in order totransmit the loads to the fundations

The building consists of a central hall, with a V-shaped two-storey officewing at each end. Each office floor has a surface area of about 1 000m.The service rooms are in the central office and in separate subsidiarybuildings. The storey heights are very large: 5,6m gross (4,3m net) in theoffice wings, while the central hall is 7,2m high.

The load-bearing structure is made of steel. There are 19 columns in each1 000 square meters of wing. The frame is 8,0m between centres.The distance between columns varies between 8,15 to 9,0m.

When the building was originally designed, the possibility of adding anextra floor to the end wings at a later stage was taken into account in thedesign and construction.

7.1.1

7.1.2


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7. Additions

The main requirements were:

l reducing the storey height in the office

wings from 5,6m to 3,75m, so thatwithin the existing building volumethe usable office floor space could beincreased from 4 000m to 6 000m,

l the design of a new, completelyinsulated faade, whilst retaining theoriginal features of the building,

l the creation of new utility provisions inboth wings, such as lift, stairs and toilets,

l the following solution was adopted in orderto realise the first phase (Figure 7.1.2):

- fit a steel construction for thenew floor at 8,25m;

- assemble the temporary supportconstruction beneath this;

- shorten the inferior columns by 1,85mand keep these column sections;

- put the jacks in place;- release the column division and allow

the floor to be lowered by 1,85m;- replace the column sections and weld

the whole structure together.

This example shows the potential of steel forimproving the vertical additions. In Torontoan existing building structure of six storeysmade of reinforced concrete was designedto be super elevated by four further storeysin the same material (Figure 7.2.1).

7.2 Vertical extension superelevation: Building in VictoriaStreet, Toronto (Canada)

7.1.1 The Van Leer Office building in Amstelveen (The Netherlands)7.1.2 The different phases of the transformation of the steel structure from two stories to three stories7.2.1 The original r.c. building in Victoria Street (Toronto, Canada)

Contrary to the initial choice, it was later decidedto use steel for the additional structure.Thanks to this, instead of four storeys, itwas possible to add eight new storeys.Therefore, the super elevated building nowconsists of fourteen storeys instead often, with a significant increase in volume incontrast with the initial building plans.

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7. Additions

The Jolly Hotel in Caserta originally consisted ofthree buildings: two six-storey r.c. buildings andone three-storey masonry building in between.

A request was made to extend the intermediatemasonry building by more than three storeysin order to be level with the adjacent two. Asthe conditions of the masonry walls, werenot able to withstand this type of extension,even with some consolidation works, analternative solution based on the use ofsteelwork was proposed. It consisted of the

construction of five tall portal frames, fromwhich the three new floors were suspended.

The added steel frames, outside and in themiddle of the new faade, contributed toimprove the aesthetic of the building.

7.4 Vertical extensionby suspension: the JollyHotel in Caserta (Italy)


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7. Additions

The restoration of the Reichstag in Berlin wasthe subject of an international competition wonby Sir Norman Foster. The basis of the designwas the replacement of the original dome with anew huge transparent hemisphere, with a centralcone reflecting the natural light directly into thebuilding and also used as natural cooling system.

The dome, measuring 38m in diameter andwith a height of 23.5m, stands in the centreof the building 24m above the ground level. Itsstructure is composed of 24 curved ribs, rising

from the bottom box girder ring, completedby 17 horizontal rings. A perimeter spiroidalramp forms an integral part of the dome itself,acting like very stiff ring beams (Figure 7.5.1).

The modern Working Parliament is locatedbelow the dome, containing the newestcommunication, office and workingtechniques. The balconies have been builtby using steelwork (Figure 7.5.2).

7.5 The Reichstagin Berlin (Germany)

7.5.2

7.5.1


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7. Additions

An extension that includes reconstructionwas built in the former administration buildingand pit-hoist of the Coal-Mine Nordsternin Gelsenkirchen, which was converted intoan office and leisure centre (Figure 7.6.1).

A vertical addition was carried out in thegymnasium of Schwbisch-Hall whichenables the use of existing buildings underconstruction conditions (Figure 7.6.2).

The Stadtlagerhaus in Hamburg

harbour, next to the famous fish market,exemplifies the modern combination ofliving and working at the waterfront ofthe city of Hamburg (Figure 7.6.3).

7.5.1 The new steel and glass dome of the German National Parliament, former Reichstag, in Berlin7.5.2 The steelwork for the balconies of the Working Parliament of the Reichstag in Berlin (Germany)7.6.1 The Coal Mine Nordstern in Gelsenkirchen (Germany) after restoration7.6.2 The vertical addition of a High-School Complex in Schwbisch-Hall (Germany)7.6.3 The Stadtlagerhaus in the Hamburg harbour (Germany) as a result of the restoration of an old storage and silo building

7.6 Various horizontaland verticalextensions using

steelwork in Germany

7.6.2 7.6.3

7.6.1


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Cognac-Jay House Old Peoples Home, France


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7. Additions

BELGIUM

p. 67-69Atomium - BrusselsClient: ASBL Atomium VZWArchitect: Conix ArchitectenEngineering firms: Bgroup-Arbeitsgemeinschaft, GeocalPhotographers: Marc Detiffe, asbl Atomium:Marie-Franoise Plissart, Luc Tourlous

FRANCE

p. 17Dames de France - PerpignanClient: City of PerpignanArchitect: Philippe PousEngineering firm: Soulas-Etec

p. 76Cognac-Jay House Old PeoplesHome, Rueil-MalmaisonClient: Cognac-Jay foundationArchitects: Jean Nouvel, Didier BraultEngineering firm: BETPhotographer: Philippe Ruault

GERMANY

p. 16Christus Pavillon - HannoverArchitects: Gerkan, Marg + Partner Architects

References

LUXEMBOURG

p. 23Abbey of Neumnster - LuxembourgClient: Ministry of the Public WorksArchitect: J. EwertEngineering firm: IncaPhotographer: Menn Bodson

SPAIN

p. 2-3, 5, 26-27Reina Sofia National Art CentreMuseum - MadridClient: Sofia National Art Centre MuseumArchitects: Jean Nouvel und Alberto MedemEngineering firms: Esteyco, JG

y asociados, Higini ArauPhotographers: Joaquim Corts,Jos Luis Municio, Ana Mll

p. 41Bernabeu Football Stadium - MadridClient: Real Madrid C. F.Architect: Estudio LamelaPhotographers: Estudio Lamela,Francisco Pablos Laso


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Technicalassistance& Finishing

Finishing

As a complement to the technical capacitiesof our partners, we are equipped withhigh-performance finishing tools andoffer a wide range of services, such as:

l drillingl flame cuttingl T cut-outsl notchingl camberingl curvingl straighteningl cold sawing to exact lengthl welding and fitting of studsl shot and sand blastingl surface treatment

Technical assistance

We are happy to provide you with free technicaladvice to optimise the use of our productsand solutions in your projects and to answer

your questions about the use of sectionsand merchant bars. This technical advicecovers the design of structural elements,construction details, surface protection,fire safety, metallurgy and welding.

Our specialists are ready to support yourinitiatives anywhere in the world.

To facilitate the design of your projects, we alsooffer software and technical documentation that

you can consult or download from our website:

www.arcelormittal.com/sections

Building & ConstructionSupportAt ArcelorMittal we also have a team ofmulti-product professionals specialising inthe construction market: the Building andConstruction Support (BCS) division.

A complete range of products andsolutions dedicated to construction in allits forms: structures, faades, roofing,etc. is available from the website

www.constructalia.com


81/8479

Although every care has been taken during the production of this brochure, we regret

that we cannot accept any liability in respect of any incorrect information it may contain

or any damages which may arise through the misinterpretation of its contents.

Your partners

ArcelorMittalCommercial Sections66, rue de LuxembourgL-4221 Esch-sur-AlzetteLuxembourgTel: +352 5313 3014Fax: +352 5313 3087


We operate in more than 60 countrieson all five continents. Please have a look

at our website under About us to findour local agency in your country.


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Notes


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Federico M. Mazzolani Department of Structural Analysis and Design, University of Naples Federico II, Naples, Italy


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ArcelorMittalCommercial Sections

66, rue de LuxembourgL-4221 Esch-sur-AlzetteLUXEMBOURGTel. + 352 5313 3014Fax + 352 5313 3087


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